1. Field of the Invention
This invention relates to development of novel binding proteins (including mini-proteins) by an iterative process of mutagenesis, expression, chromatographic selection, and amplification. In this process, a gene encoding a potential binding domain, said gene being obtained by random mutagenesis of a limited number of predetermined codons, is fused to a genetic element which causes the resulting chimeric expression product to be displayed on the outer surface of a virus (especially a filamentous phage) or a cell. Chromatographic selection is then used to identify viruses or cells whose genome includes such a fused gene which coded for the protein which bound to the chromatographic target.